1. The Phoenix Project Usage – Germaine Cornélissen © 2007 Germaine G Cornelissen-Guillaume. Copying and distribution of this document is permitted in any medium, provided this notice is preserved. www.phoenix.tc-ieee.org

2. Problem: Blood pressure is highly variable (from moment to moment, from one day to another, …). Are fixed limits such as 140/90 mmHg (systolic/diastolic BP) warranted?

3. BP variability is not trivial: Abnormal variability in blood pressure and/or heart rate is associated with an increased vascular disease risk, even in the absence of “hypertension”. Abnormalities include: 1. a decreased standard deviation of HR 2. an elevated pulse pressure (SBP-DBP) 3. an excessive circadian BP variation (CHAT) 4. an odd timing of the circadian BP rhythm

4. Sphygmochron Analysis: Data are analyzed parametrically (to assess the circadian charcateristics) and non-parametrically (to check for BP/HR excess or deficit), using reference limits that are time-specified and further qualified by gender and age.

5. Treatment: Certain BP/HR abnormalities can be treated by selecting the appropriate medication and a suitable time of administration. For instance, reducing CHAT is associated with better outcomes.

6. Merit of chronobiologic approach Higher predictive value of the circadian amplitude and phase interpreted in the light of gender-and age-specified norms as compared to day-night ratio.

7. Summary Blood pressure is highly variable. Abnormal BP/HR variability is not trivial as it is associated with increased vascular disease risk. Parametric and non-parametric endpoints are interpreted in the light of norms that are specified as a function of circadian stage, gender, and age. Certain BP/HR variability disorders can be treated and their treatment is associated with improved outcomes. A chronobiologic approach relying on the circadian amplitude and phase interpreted in the light of time-, gender-, and age-specified norms, has better predictive value than day-night ratios.